Subaru drivetrain slack
 

Why is it that Subaru design their cars with so much drivetrain slack?

With stock gearbox mounts, suspension and bushes the slack wasn't that noticeable - as it was assimilated by the otherwise soft setup.

Now, with coilovers and all rubber bushings eliminated - the drivetrain slack spoils the whole experience. During a throttle on-off-on transition, I can literally feel and hear the drivetrain picking up the slack <clack-clack>

Can the differentials be run with tighter backlash and higher preloads than specified in the service manual? Does it help?

No, this is NOT down to wear. Converted from 5MT to 6MT and R180, no difference.

Do you still have a sprung center in the clutch?